The goal of this research is to identify the molecular basis of primary germ layer formation in vertebrate embryos. This fundamental cell fate decision is only partially understood. Recently, it has been discovered that in Xenopus, mesoderm and endoderm cell fates are specified by maternal transcription factors. In this study, we focus on what determines the ectoderm germ layer. We have identified ectoderm-inducing activities in pools of maternal cDNAs, and we will use expression cloning to identify these genes. Subsequently we will characterize the expression of these genes and determine their roles in development through loss-of-function experiments. Understanding the formation of the ectoderm will be a major step forward in understanding cell fate determination in early development.